1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a DC type plasma display panel for back light capable of realizing high brightness and being free from pollution due to mercury (Hg).
2. Description of the Related Art
A liquid crystal display device has been substituted for a Cathode-ray tube (CRT) in a terminal of information system and video unit since it has advantages of light weight, thin thickness and low power consumption compared with the CRT. Recently, the liquid crystal display device has realized wide viewing angle and is prevented a color shift, thereby obtaining high quality screen. Therefore, it is widely used in a notebook PC and a computer monitor market. In addition, it is used in TV.
The liquid crystal display device cannot emit light by oneself differently from the CRT, so that back light unit is additionally included therein as a light source. The back light unit comprises a lamp as a practical light source, a light guide plate and a plurality of optical sheets, wherein the lamp is generally a fluorescent lamp.
However, there are limitations in employing the fluorescent lamp using mercury (Hg) due to pollution problem. Moreover, it is required that the light guide plate have a predetermined thickness in order to improve uniformity and brightness of light from the fluorescent lamp, so that the light guide plate functions as a cause increasing the thickness of liquid crystal display device. As a result, it is difficult to use the conventional back light unit having the above structure as the light source in the future.
Therefore, it has been proposed a technique that plasma display panel is used as a light source in order to prevent pollution due to Hg and to decrease the thickness of liquid crystal display device.
The plasma display panel is a kind of display devices in the same way as the liquid crystal display. The plasma display panel is used gas discharge in order to display a picture, thereby being free form the pollution due to Hg. The plasma display panel generally has a complicated structure, but, as shown in FIGS. 1 to 3, the plasma display panel for back light has a thin structure that a rear substrate 2 and a front substrate 4 comprising a pair of discharge electrodes 3a, 3b, 3c are sealed by seal paste 5 with discharge gas (not shown) filled therein. Therefore, it can be advantageously applied to realize thin thickness of liquid crystal display device. In the drawings, the FIG. 1 shows an opposite discharge type plasma display panel and FIGS. 2 and 3 show surface discharge type plasma display panels.
However, the conventional plasma display panel for back light has a disadvantage of low brightness since gas discharge is not sufficiently generated in a discharge space, so that it is difficult to realize high quality screen in the liquid crystal display device having the plasma display panel for back light.
Moreover, the conventional plasma display panel for back light has a disadvantage of high cost since it is generally manufactured in AC type and through printing, drying, firing and exposing processes, so that it is difficult to employ substitute for lamp as a light source.
Therefore, an object of the present invention is to provide DC type plasma display panel for back light capable of obtaining high brightness.
And, another object of the present invention is to provide DC type plasma display panel for back light capable of reducing the production cost.
In order to accomplish the above object, Dc type plasma display panel according to the present invention comprises: a rear substrate functioning as a cathode electrode, having a first groove formed at the edge of the upper side and a first oxide layer formed to surround the edge of the upper side including the first groove and all over the down side thereof; an anode electrode plate arranged over the rear substrate with a predetermined distance, having a second groove formed at the edge of the down side corresponding to the first groove of the rear substrate and a second oxide layer formed, to surround the edge of the down side including the second groove and the edge of the upper side, having a plurality of holes therein; a seal frame sealing the rear substrate and the anode electrode plate, wherein the down side of the seal frame is put in the first groove of the rear substrate and the upper side of the seal frame is put in the second groove of the anode electrode plate, and a third oxide layer is formed on the outer side of the seal frame; a front substrate arranged over the anode electrode plate with a predetermined distance, having a fluorescent layer formed on the upper side thereof opposite to the anode electrode plate; a plurality of spacers interposed between the anode electrode plate and the front substrate; seal paste sealing the edges of the anode electrode plate and the front substrate; and discharge gas filled in the space between the rear substrate and the anode electrode plate and between the anode electrode plate and the front substrate.
The first and the second oxide layers are formed to the region adjacent to the seal frame from the inner side thereof and the holes are formed at the region of the anode electrode plate unformed the second oxide layer in the inner side of the seal frame.
The first and the second oxide layers are formed to the region separated with a predetermined distance from the seal frame in the inner side thereof and the holes are formed at the region adjacent to the second groove of the anode electrode plate formed the second oxide layer in the inner side of the seal frame.
The above objects, and other features and advantages of the present invention will become more apparent after reading the following detailed description when taken in conjunction with the drawings.